I want to make akyl iodides from alcohols. Mainly methyl iodide. I don't have phosphorus, so I started thinking about using sulfur instead. On the
science madness wiki it says that disulfur dichloride reacts with alcohols, but it doesn't give any specifics. Would reacting disulfur diiodide with
methanol give methyl iodide, similar to how PI3 works?Fery - 26-1-2021 at 23:09
Does S2I2 even exist at stp? I say that bcoz I remember something about Sbr2 exists but S2br2 doesn't or something like that.At least not above like
-80'c.njl - 27-1-2021 at 05:51
While i'm sure something along these lines could end up working, I can't find many reliable sources that describe sulfur/iodine compounds. Both SBr
and S2Br2 exist and are relatively stable, but I think the S-I bond would be quite weak. Alternatively, there is the multistep sulfur-iodine process
for splitting water, one stage of which entails the reduction of I2 to HI by sulfur dioxide. This actually seems quite useful since the reactants are
available (I2, H2O, SO2 from burning sulfur) and the products are HI and H2SO4, both of which you would want for making alkyl iodides. This process
might even proceed via a sulfur iodide intermediate, but I couldn't say for sure.
Edit: I'm pretty sure H2S can also reduce iodine to iodide, so there are options.
[Edited on 1-27-2021 by njl]Triflic Acid - 27-1-2021 at 12:49
What solvent would you be using? As far as I know elemental sulfur and iodine are most soluble together in CS2 and toluene. CS2 is not otc and
dangerous, and sulfur is still only mildly soluble in toluene. Dropping iodine into molten sulfur doesn't sound pleasant either. I think SO2 and H2S
are going to be the easiest reagents to use for reducing iodine. If you're comfortable working with either that is. Amos - 28-1-2021 at 06:14
You should try this method and also try the aluminum foil method with the same quantities of iodine and methanol. It'd be interesting to compare the
two methods, assuming the sulfur one works.
I have always used aluminum foil in the form of little balls, and I add a drop of hydrochloric acid once the mixture is warmed up to expose the
aluminium. Be sure on any attempt to use a long, very, very cold condenser, or even better, distill into a 2-neck flask with a second condenser
hooked up on the other neck.
[Edited on 1-28-2021 by Amos]Bedlasky - 28-1-2021 at 13:53
Does S2I2 even exist at stp? I say that bcoz I remember something about Sbr2 exists but S2br2 doesn't or something like that.At least not above like
-80'c.
S2I2 decomposes at -30°C. Polysulfur diiodide SxI2 also exist, it's unstable, but it will be more stable than S2I2.unionised - 28-1-2021 at 14:24
Sometimes a few weeks in the lab can save you nearly an hour in the library.
I was actually thinking of the alcohol as the solvent, and the sulfur as a suspension that forms some kind of sulfur iodide in situ and then reacts
with the alcohol solvent. Kind of like how you iodate alcohols with red P suspension and alcohol solvent.clearly_not_atara - 29-1-2021 at 12:09
Does S2I2 even exist at stp? I say that bcoz I remember something about Sbr2 exists but S2br2 doesn't or something like that.At least not above like
-80'c.
S2Br2 exists and is stable under standard conditions. However, it does not form readily upon combination of liquid bromine and elemental sulfur.
Recommendations for its preparation invariably recommend heating the mixture.
Somehow, when sulfur and bromine are used to make acetic anhydride, the acetate ions catalyze the reaction so that it will proceed under standard
conditions. However, since they destroy the product S2Br2 in the process, this is not a useful way to make sulfur monobromide.
All sulfur dihalides are unstable, SF2 especially so (disproportionates), but even SCl2 slowly releases chlorine.draculic acid69 - 2-2-2021 at 04:05
Does S2I2 even exist at stp? I say that bcoz I remember something about Sbr2 exists but S2br2 doesn't or something like that.At least not above like
-80'c.
S2I2 decomposes at -30°C. Polysulfur diiodide SxI2 also exist, it's unstable, but it will be more stable than S2I2.
Yes this is what I was thinking of.got it confused with sulfur dibromide.symboom - 2-2-2021 at 04:28
Damn prepchem has so many damn ads and requires registration to search here is the link
Two hundred and eighty-five grams of iodine are suspended in 250 ml of water contained in a one-liter filter flask fitted with a wide gas inlet tube
that reaches to about one-half inch from the bottom of the vessel. Under the hood, a stream of hydrogen sulfide is passed into the suspension as
rapidly as it can be absorbed. Some heat is evolved and the flask may be cooled in a water bath. Frequent agitation is necessary to prevent a coating
of sulfur from forming over the initially undissolved iodine; as the reaction progresses, the iodine dissolves in the hydriodic acid already formed.
The sulfur, which settles out as a spongy mass on the bottom of the flask, is separated from the pale brown liquid that is finally produced by
decantation, and filtration through a plug of glass wool. The filtrate is refiuxed to remove excess dissolved hydrogen sulfide, using boiling chips to
prevent bumping. Five milliliters of 30% hypophosphorous acid are added, the mixture is fractionated through a short efficient column, and the portion
boiling at 125-127° C is collected. Yield 425~450 g of 57 % hydroiodic acid.
Hydriodic acid that is stored in a dark all-glass container in the refrigerator, preferably under an inert gas, remains colorless for 4-3 months. If
the treatment with hypophosphorus acid is omitted, the resulting acid is straw-colored and it deteriorates more rapidly on standing; only
distillation in hydrogen or carbon dioxide gives a colorless material.
Inorganic laboratory preparations 145-147, 1962
[Edited on 2-2-2021 by symboom]Triflic Acid - 14-3-2021 at 20:55
I am planning on running this experiment, but I can't find a single paper outlining the reaction of sulfur chlorides with alcohols. Does anyone have
such a paper?
